Process for making diaryl sulfones

ABSTRACT

A process for preparing diaryl sulfones, such as 4,4′-dichlorodiphenylsulfone is disclosed. The process comprises contacting an aryl compound with sulfur trioxide to provide a benzene sulfonic acid. The benzene sulfonic acid is coupled to additional aryl compound in the presence of a catalyst. During the coupling step, the additional aryl compound is continuously added while water is removed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Application Ser. No. 62/173,283, filed Jun. 9, 2015, whichis incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The invention described herein pertains to a process for making diarylsulfones, such as 4,4′-dihalodiphenyl sulfones.

BACKGROUND OF THE INVENTION

Several processes for preparing diaryl sulfones, such as4,4′-dichlorodiphenylsulfone (DCDPS) are known. Such processes mayutilize various paths to make diaryl sulfones starting various arylstarting materials, such as from chlorobenzene.

In one exemplary diaryl sulfone preparation described in U.S. Pat. No.4,937,387, DCDPS is produced from sulfur trioxide and monochlorobenzenein a two-step process. The first step is the reaction ofmonochlorobenzene with sulfur trioxide to form chlorobenzene sulfonicacid (CBSA). The second step is the reaction of chlorobenzene sulfonicacid with monochlorobenzene. The reaction in reported to result in anaverage conversion to DCDPS of 20.8% based on CBSA and sulfuric acidfeed (Table I). Additional steps are taken to recover unreacted CBSA forrepeating the second step to form additional DCDPS.

In another exemplary diaryl sulfone preparation described in U.S. Pat.No. 4,983,773, DCDPS is formed from chlorobenzene and sulfonic acid withadded boric acid in a one-step process. Purification is performed byselective washing with a solvent, by fractional crystallization or bycentrifuging. The reported yield is 84%

In yet another exemplary diaryl sulfone preparation described in WOPatent Publication No. WO 2012/143281, DCDPS is formed fromchlorobenzene, sulfuric acid, and trifluoroacetic anhydride (TFAA) as adehydrating reagent. The overall reaction does not result in water as aproduct because TFAA is converted to trifluoroacetic acid (TFA). Thebest reported yield is 100%. However, this process uses stoichiometricamounts of TFAA.

There remains a needs for a more economical process for producing diarylsulfones, such as 4,4′-dichlorodiphenylsulfone. Specifically, thereremains a need for a process for efficiently producing diaryl sulfones,such as DCDPS, in high yield and high selectivity with minimal byproductformation.

SUMMARY OF THE INVENTION

In some embodiments, the disclosure provides a process for preparing asulfone of the formula

wherein X¹ and X² are independently H, halogen, C₁-C₆ alkyl, C₆-C₁₀aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl,wherein each hydrogen atom in C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl is independentlyoptionally substituted with a halogen, C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl; the processcomprising

a. a coupling step comprising contacting a sulfonic acid of the formula

with an aryl compound of the formula

in the presence of a catalyst, wherein resulting water is removed duringthe coupling step.

In some embodiments, the disclosure provides a process for preparing asulfone of the formula

wherein X¹ and X² are independently H, halogen, C₁-C₆ alkyl, C₆-C₁₀aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl,wherein each hydrogen atom in C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl is independentlyoptionally substituted with a halogen, C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl; the processcomprising

a. a first step contacting an aryl reactant of the formula

with sulfur trioxide to provide a first product mixture comprising asulfonic acid of the formula

and

b. a coupling step comprising contacting the sulfonic acid of theformula

with an aryl halide of the formula

in the presence of a catalyst, wherein resulting water is removed duringthe coupling step.

In some embodiments, the disclosure provides a process for preparing asulfone of the formula

wherein X¹ and X² are independently halogens, the process comprising acoupling step comprising contacting a sulfonic acid with an aryl halidein the presence of a catalyst, wherein resulting water is removed duringthe coupling step.

In some embodiments, the disclosure provides a process for preparing asulfone of the formula

wherein X¹ and X² are independently halogens, the process comprising afirst step comprising contacting an aryl halide reactant with sulfurtrioxide to provide a first product mixture comprising a sulfonic acid,and a coupling step comprising contacting the sulfonic acid with an arylhalide in the presence of a catalyst, wherein resulting water is removedduring the coupling step.

Embodiments of the invention are further described by the followingenumerated clauses. It will be understood that any of the embodimentsdescribed herein can be used in connection with any other embodimentsdescribed herein to the extent that the embodiments do not contradictone another:

1. A process for preparing a sulfone of the formula

wherein X¹ and X² are independently halogens, the process comprising:

a coupling step comprising contacting a sulfonic acid of the formula

wherein X¹ is a halogen, with an aryl halide of the formula

wherein X² is a halogen, in the presence of a catalyst, whereinresulting water is removed during the coupling step.

1a. A process for preparing a sulfone of the formula

wherein X¹ and X² are independently H, halogen, C₁-C₆ alkyl, C₆-C₁₀aryl, —C₁-C₆ (C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl, wherein eachhydrogen atom in C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl),—OC₁-C₆ alkyl or —OC₆-C₁₀ aryl is independently optionally substitutedwith a halogen, C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl),—OC₁-C₆ alkyl or —OC₆-C₁₀ aryl; the process comprising

a. a coupling step comprising contacting a sulfonic acid of the formula

with an aryl compound of the formula

in the presence of a catalyst, wherein resulting water is removed duringthe coupling step.

2. The process of any of the preceding clauses, wherein X¹ and X² areCl.

3. The process of any of the preceding clauses, wherein the crude yieldof the coupling step, as determined by the sulfone relative to thesulfonic acid, is about 50% to about 100%, about 55% to about 100%,about 60% to about 100%, about 65% to about 100%, about 70% to about100%, about 75% to about 100%, about 80% to about 100%, about 85% toabout 100%, about 50% to about 95%, about 55% to about 95%, about 60% toabout 95%, about 65% to about 95%, about 70% to about 95%, about 75% toabout 95%, about 80% to about 95%, about 85% to about 95%, about 50% toabout 90%, about 55% to about 90%, about 60% to about 90%, about 65% toabout 90%, about 70% to about 90%, about 75% to about 90%, about 80% toabout 90%, or about 85% to about 90%.

4. The process of any of the preceding clauses, wherein the crude yieldof the coupling step, as determined by the sulfone relative to thesulfonic acid, is about 60% to about 95%.

5. The process of any of the preceding clauses, wherein the crude yieldof the coupling step, as determined by the sulfone relative to thesulfonic acid, is about 82% to about 93%.

6. The process of any of the preceding clauses, wherein the purifiedyield of the coupling step, as determined by the sulfone relative to thesulfonic acid, is about 40% to about 95%, about 45% to about 95%, about50% to about 95%, about 55% to about 95%, about 60% to about 95%, about65% to about 95%, about 70% to about 95%, about 75% to about 95%, about80% to about 95%, 40% to about 90%, about 45% to about 90%, about 50% toabout 90%, about 55% to about 90%, about 60% to about 90%, about 65% toabout 90%, about 70% to about 90%, about 75% to about 90%, about 80% toabout 90%, 40% to about 85%, about 45% to about 85%, about 50% to about85%, about 55% to about 85%, about 60% to about 85%, about 65% to about85%, about 70% to about 85%, about 75% to about 85%, or about 80% toabout 85%.

7. The process of any of the preceding clauses, wherein the purifiedyield of the coupling step, as determined by the sulfone relative to thesulfonic acid, is about 50% to about 85%.

8. The process of any of the preceding clauses, wherein the purifiedyield of the coupling step, as determined by the sulfone relative to thesulfonic acid, is about 70% to about 75%.

9. The process of any of the preceding clauses, wherein the couplingstep is initiated under anhydrous conditions.

10. The process of any of the preceding clauses, wherein the couplingstep is initiated with less than about 10 wt % water, less than about 5wt % water, less than about 1 wt % water, or less than about 0.5 wt %water.

11. The process of any of the preceding clauses, wherein the couplingstep is initiated with less than about 10 wt % water.

12. The process of any of the preceding clauses, wherein the resultingwater is removed continuously during the coupling step.

13. The process of any of the preceding clauses, wherein the resultingwater is removed by distillation.

14. The process of any of the preceding clauses, wherein theconcentration of water throughout the coupling step is less than about10 wt % water, less than about 5 wt % water, less than about 1 wt %water, or less than about 0.5 wt % water.

15. The process of any of the preceding clauses, wherein theconcentration of water throughout the coupling step is less than about10 wt % water.

16. The process of any of the preceding clauses, wherein the couplingstep is performed without a dehydrating reagent.

17. The process of any of the preceding clauses, wherein theconcentration of the catalyst relative to all components of the couplingstep, when the coupling step is initiated, is about 0.1 wt % to about 10wt %, about 0.1 wt % to about 5 wt %, about 0.5 wt % to about 2 wt %,about 0.7 wt % to about 1.1 wt %, or about 0.9 wt %.

18. The process of any of the preceding clauses, wherein theconcentration of the catalyst relative to all components of the couplingstep, when the coupling step is initiated, is about 0.1 wt % to about 5wt %.

19. The process of any of the preceding clauses, wherein theconcentration of the catalyst relative to all components of the couplingstep, when the coupling step is initiated, is about 0.7 wt % to about1.1 wt %.

20. The process of any of the preceding clauses, wherein the amount ofthe catalyst relative to the sulfonic acid, when the coupling step isinitiated, is about 0.01 equivalent to about 1 equivalent, about 0.01equivalent to about 0.5 equivalent, about 0.01 equivalent to about 0.1equivalent, about 0.01 to about 0.075 equivalent, about 0.02 equivalentto about 1 equivalent, about 0.02 equivalent to about 0.5 equivalent,about 0.02 equivalent to about 0.1 equivalent, about 0.02 to about 0.075equivalent, about 0.025 equivalent, or about 0.05 equivalent.

21. The process of any of the preceding clauses, wherein theconcentration of the catalyst relative to the sulfonic acid, when thecoupling step is initiated, is about 0.01 equivalent to about 0.1equivalent.

22. The process of any of the preceding clauses, wherein theconcentration of the catalyst relative to the sulfonic acid, when thecoupling step is initiated, is about 0.025 equivalent to about 0.05equivalent.

23. The process of any of the preceding clauses, wherein the catalyst isselected from the group consisting of a boron catalyst, an ironcatalyst, a zinc catalyst, a tin catalyst, a titanium catalyst, azirconium catalyst, a bismuth catalyst, an antimony catalyst, a silicacatalyst, a metal sulfate catalyst, a metal oxide catalyst, a sulfonicacid catalyst, an iodine catalyst, or a combination thereof.

24. The process of any of the preceding clauses, wherein the catalyst isselected from the group consisting of aluminum oxide, antimony oxide,zirconium oxide, bismuth oxide, boric anhydride, boric acid, ferricoxide, stannic oxide, titanium oxide, titanium sulfate, zinc oxide,iodine, lithium iodide, methane sulfonic acid, trifluoromethane sulfonicacid, silica and dimethylsulfate.

25a. The process of any of the preceding clauses, wherein the catalystis aluminum oxide.

25b. The process of any of the preceding clauses, wherein the catalystis zirconium oxide.

25c. The process of any of the preceding clauses, wherein the catalystis bismuth oxide.

25d. The process of any of the preceding clauses, wherein the catalystis boric anhydride.

25e. The process of any of the preceding clauses, wherein the catalystis boric acid. 25f. The process of any of the preceding clauses, whereinthe catalyst is ferric oxide.

25g. The process of any of the preceding clauses, wherein the catalystis stannic oxide.

25h. The process of any of the preceding clauses, wherein the catalystis titanium oxide.

25i. The process of any of the preceding clauses, wherein the catalystis titanium sulfate.

25j. The process of any of the preceding clauses, wherein the catalystis zinc oxide.

25k. The process of any of the preceding clauses, wherein the catalystis iodine.

25l. The process of any of the preceding clauses, wherein the catalystis lithium iodide.

25m. The process of any of the preceding clauses, wherein the catalystis methane sulfonic acid.

25n. The process of any of the preceding clauses, wherein the catalystis trifluoromethane sulfonic acid.

25o. The process of any of the preceding clauses, wherein the catalystis silica.

25p. The process of any of the preceding clauses, wherein the catalystis dimethylsulfate.

25q. The process of any of the preceding clauses, wherein the catalystis antimony oxide.

26. The process of any of clauses 1 or 3-25, wherein the coupling stepresults in less than 20% of a 2,4′ isomer of the formula

wherein X¹ and X² are independently H, halogen, C₁-C₆ alkyl, C₆-C₁₀aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl,wherein each hydrogen atom in C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl is independentlyoptionally substituted with a halogen, C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl, as determined bythe 2,4′ isomer relative to all sulfone products.

27. The process of any of clauses 1 or 3-26, wherein the coupling stepresults in less than 10% of a 2,4′ isomer of the formula

wherein X¹ and X² are independently H, halogen, C₁-C₆ alkyl, C₆-C₁₀aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl,wherein each hydrogen atom in C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl is independentlyoptionally substituted with a halogen, C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl, as determined bythe 2,4′ isomer relative to all sulfone products.

28. The process of any of clauses 1 or 3-27, wherein the coupling stepresults in less than 20% of a 3,4′ isomer of the formula

wherein X¹ and X² are independently H, halogen, C₁-C₆ alkyl, C₆-C₁₀aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl,wherein each hydrogen atom in C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl is independentlyoptionally substituted with a halogen, C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl, as determined bythe 3,4′ isomer relative to all sulfone products.

29. The process of any of clauses 1 or 3-28, wherein the coupling stepresults in less than 10% of a 3,4′ isomer of the formula

wherein X¹ and X² are independently H, halogen, C₁-C₆ alkyl, C₆-C₁₀aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀) aryl,wherein each hydrogen atom in C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl is independentlyoptionally substituted with a halogen, C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl, as determined bythe 3,4′ isomer relative to all sulfonic products.

30. The process of any of clauses 26-29, wherein X¹ and X² are Cl.

31. The process of any of the preceding clauses, wherein the aryl halideor aryl compound is added to the sulfonic acid continuously during thecoupling step.

32. The process of any of the preceding clauses, wherein the aryl halideor aryl compound is added to the sulfonic acid continuously for about0.5 hour to about 20 hours, about 1 hour to about 20 hours, about 2hours to about 20 hours, about 7 hours to about 20 hours, about 9 hoursto about 20 hours, about 10 hours to about 20 hours, about 0.5 hour toabout 15 hours, about 1 hour to about 15 hours, about 2 hours to about15 hours, about 7 hours to about 15 hours, about 9 hours to about 15hours, about 10 hours to about 15 hours, about 0.5 hour to about 13hours, about 1 hour to about 13 hours, about 2 hours to about 13 hours,about 7 hours to about 13 hours, about 9 hours to about 13 hours, about10 hours to about 13 hours, about 0.5 hour to about 12 hours, about 1hour to about 12 hours, about 2 hours to about 12 hours, about 7 hoursto about 12 hours, about 9 hours to about 12 hours, about 10 hours toabout 12 hours, or about 10 hours.

33. The process of any of the preceding clauses, wherein the aryl halideor aryl compound is added to the sulfonic acid continuously for about 7hours to about 13 hours.

34. The process of any of the preceding clauses, wherein the aryl halideor aryl compound is added to the sulfonic acid continuously for about 9hours to about 12 hours.

35. The process of any of the preceding clauses, wherein the aryl halideor aryl compound is added to the sulfonic acid continuously for about 10hours.

36. The process of any of the preceding clauses, wherein the aryl halideor aryl compound is added to the sulfonic acid continuously at the sametime that water is removed continuously from the sulfonic acid.

37. The process of any of the preceding clauses, wherein the aryl halideor aryl compound is added to the sulfonic acid continuously at the sametime that wet chlorobenzene is removed continuously from the sulfonicacid.

38. The process of any of the preceding clauses, wherein the aryl halideor aryl compound is added at a flow rate of about 0.1 mL/min to about 10mL/min, about 0.5 mL/min to about 5 mL/min, about 0.5 mL/min to about 3mL/min, or about 1.5 mL/min.

39. The process of any of the preceding clauses, wherein the aryl halideor aryl compound is added at a flow rate of about 1.5 mL/min.

40. The process of any of the preceding clauses, wherein the couplingstep is performed at a coupling temperature of about 150° C. to about280° C., about 160° C. to about 280° C., about 170° C. to about 280° C.,about 180° C. to about 280° C., about 150° C. to about 260° C., about160° C. to about 260° C., about 170° C. to about 260° C., about 180° C.to about 260° C., about 150° C. to about 240° C., about 160° C. to about240° C., about 170° C. to about 240° C., or about 180° C. to about 240°C.

41. The process of any of the preceding clauses, wherein the couplingstep is performed at a coupling temperature of about 180° C. to about240° C.

42. The process of clause 40 or 41, further comprising increasing thecoupling temperature during the coupling step.

43. The process of any of clauses 40-42, further comprising increasingthe coupling temperature from about 180° C. to about 240° C. during thecoupling step.

44. The process of clause 42 or 43, wherein the coupling temperature isincreased continuously for about 5 minutes to about 120 minutes, about15 minutes to about 120 minutes, about 30 minutes to about 120 minutes,about 45 minutes to about 120 minutes, about 60 minutes to about 120minutes, about 90 minutes to about 120 minutes, about 5 minutes to about90 minutes, about 15 minutes to about 90 minutes, about 30 minutes toabout 90 minutes, about 45 minutes to about 90 minutes, about 60 minutesto about 90 minutes, about 5 minutes to about 60 minutes, about 15minutes to about 60 minutes, about 30 minutes to about 60 minutes, about45 minutes to about 60 minutes, about 5 minutes to about 45 minutes,about 15 minutes to about 45 minutes, about 30 minutes to about 45minutes, about 5 minutes to about 30 minutes, about 15 minutes to about30 minutes, or about 5 minutes to about 15 minutes.

45. The process of any of clauses 42-44, wherein the couplingtemperature is increased continuously for about 15 minutes to about 45minutes.

46. The process of any of clauses 42-45, wherein the couplingtemperature is increased continuously for about 30 minutes.

47. The process of any of clauses 42-46, wherein the aryl halide or arylcompound is added continuously at the same time that the couplingtemperature is increased.

48. The process of any of the preceding clauses, wherein the aryl halideor aryl compound is the solvent of the coupling step.

49. The process of any of the preceding clauses, wherein the couplingstep is performed at a pressure of about 15 psi to about 100 psi, about30 psi to about 100 psi, about 40 psi to about 100 psi, about 15 psi toabout 75 psi, about 30 psi to about 75 psi, about 40 psi to about 75psi, about 15 psi to about 60 psi, about 30 psi to about 60 psi, about40 psi to about 60 psi, about 15 psi to about 50 psi, about 30 psi toabout 50 psi, about 40 psi to about 50 psi, or about 45 psi.

50. The process of any of the preceding clauses, wherein the couplingstep is performed at a pressure of about 30 psi to about 60 psi.

51. The process of any of the preceding clauses, wherein the couplingstep is performed at a pressure of about 45 psi.

52. The process of any of the preceding clauses, further comprisingremoving the aryl halide or aryl compound from the sulfone after thecoupling step.

53. The process of any of the preceding clauses, further comprisingremoving the aryl halide or aryl compound from the sulfone bydistillation after the coupling step.

54. The process of any of the preceding clauses, further comprisingcooling the sulfone to a quenching temperature of about 50° C. to about70° C.

55. The process of any of the preceding clauses, further comprisingcooling the sulfone to a quenching temperature of about 60° C.

56. The process of any of the preceding clauses, further comprisingextracting the sulfone after the coupling step.

57. The process of any of the preceding clauses, further comprisingextracting the sulfone with an aromatic solvent after the coupling step.

58. The process of any of the preceding clauses, further comprisingextracting the sulfone with toluene after the coupling step.

59. The process of any of clauses 56-58, wherein the extracting step isperformed after removing the aryl halide or aryl compound from thesulfone.

60. The process of any of clauses 56-59, wherein the extracting stepresults in an amber colored solution comprising the sulfone.

61. The process of any of the preceding clauses, further comprisingwashing the sulfone with water.

62. The process of clause 61, wherein the washing step is performedafter extracting the sulfone.

63. The process of any clause 61 or 62, wherein the washing step resultsin the sulfone being substantial free of the sulfonic acid.

64. The process of any of the preceding clauses, further comprisingcrystallizing the sulfone.

65. The process of clause 64, wherein the crystallizing step isperformed after washing and extracting the sulfone.

66. The process of clause 64 or 65, wherein the crystallizing stepresults in the sulfone having a purity of greater than about 95%.

67. The process of any of clauses 64-66, wherein the crystallizing stepresults in the sulfone having a purity of greater than about 99%.

68. The process of any of clauses 64-67, wherein the crystallizing stepresults in the sulfone having a purity of about 99.9%.

69. The process of any of the preceding clauses, further comprising afirst step comprising contacting a reactant of the formula

wherein X¹ is a H, halogen, C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl, wherein eachhydrogen atom in C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl),—OC₁-C₆ alkyl or —OC₆-C₁₀ aryl is independently optionally substitutedwith a halogen, C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl),—OC₁-C₆ alkyl or —OC₆-C₁₀ aryl, with sulfur trioxide to provide a firstproduct mixture comprising the sulfonic acid.

70. The process of clause 69, wherein X¹ is Cl.

71. The process of clause 69 or 70, wherein the first step is performedunder anhydrous conditions.

72. The process of any of clauses 69-71, wherein the concentration ofwater in the first product mixture is less than about 10 wt % water,less than about 5 wt % water, less than about 1 wt % water, or less thanabout 0.5 wt % water.

73. The process of any of clauses 69-72, wherein the concentration ofwater in the first product mixture is less than about 10 wt % water.

74. The process of any of clauses 69-73, wherein the first step isperformed in a first reaction vessel and the first product mixture istransferred to a second reaction vessel after the first step for use inthe coupling step.

75. The process of any of clauses 69-74, wherein the first step isperformed at a sulfonation temperature of about 30° C. to about 100° C.,about 40° C. to about 100° C., about 50° C. to about 100° C., about 60°C. to about 100° C., about 30° C. to about 90° C., about 40° C. to about90° C., about 50° C. to about 90° C., about 60° C. to about 90° C.,about 30° C. to about 80° C., about 40° C. to about 80° C., about 50° C.to about 80° C., about 60° C. to about 80° C., about 30° C. to about 75°C., about 40° C. to about 75° C., about 50° C. to about 75° C., or about60° C. to about 75° C.

76. The process of any of clauses 69-75, wherein the first step occurswithout external cooling.

77. The process of any of clauses 69-76, wherein the first productmixture comprises the sulfonic acid, the aryl halide, and the sulfone.

78. The process of any of clauses 69-77, wherein the first productmixture comprises about 53% of the sulfonic acid, about 6% of the arylhalide, and about 41% of the sulfone.

79. The process of any of clauses 69-78, wherein the coupling stepcomprises adding the catalyst to the first product mixture.

80. The process of any of clauses 69-79, wherein the coupling stepcomprises adding boric acid to the first product mixture.

81. The process of any of clauses 69-80, wherein the first step and thecoupling steps are batch processes.

82. The process of any of clauses 69-80, wherein the first step is abatch process and the coupling step is a continuous process.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a flow diagram showing one embodiment of a process forpreparing dichlorodiphenyl sulfone from chlorobenzene sulfonic acid,include a coupling step and a purification step.

DETAILED DESCRIPTION

In accordance with Applicants' invention described herein, theembodiments of the numbered clauses provided in the summary above, orany combination thereof, are contemplated for combination with any ofthe embodiments described in the Detailed Description section of thispatent application.

A process in accordance with a first embodiment includes a process forpreparing a sulfone of the formula

wherein X¹ and X² are each independently H, halogen, C₁-C₆ alkyl, C₆-C₁₀aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl,wherein each hydrogen atom in C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl is independentlyoptionally substituted with a halogen, C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl.

As used herein, the term “alkyl” includes a chain of carbon atoms, whichis optionally branched and contains from 1 to 20 carbon atoms. It is tobe further understood that in certain embodiments, alkyl may beadvantageously of limited length, including C₁-C₁₂, C₁-C₁₀, C₁-C₉,C₁-C₈, C₁-C₇, C₁-C₆, and C₁-C₄, Illustratively, such particularlylimited length alkyl groups, including C₁-C₈, C₁-C₇, C₁-C₆, and C₁-C₄,and the like may be referred to as “lower alkyl.”

Illustrative alkyl groups include, but are not limited to, methyl,ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl,pentyl, 2-pentyl, 3-pentyl, neopentyl, hexyl, heptyl, octyl, and thelike. Alkyl may be substituted or unsubstituted. Typical substituentgroups include cycloalkyl, aryl, heteroaryl, heteroalicyclic, hydroxy,alkoxy, aryloxy, mercapto, alkylthio, arylthio, cyano, halo, carbonyl,oxo, (═O), thiocarbonyl, O-carbamyl, N-carbamyl, O-thiocarbamyl,N-thiocarbamyl, C-amido, N-amido, C-carboxy, O-carboxy, nitro, andamino, or as described in the various embodiments provided herein. Itwill be understood that “alkyl” may be combined with other groups, suchas those provided above, to form a functionalized alkyl. By way ofexample, the combination of an “alkyl” group, as described herein, witha “carboxy” group may be referred to as a “carboxyalkyl” group. Othernon-limiting examples include hydroxyalkyl, aminoalkyl, and the like.

As used herein, the term “aryl” refers to an all-carbon monocyclic orfused-ring polycyclic groups of 6 to 12 carbon atoms having a completelyconjugated pi-electron system. It will be understood that in certainembodiments, aryl may be advantageously of limited size such as C₆-C₁₀aryl. Illustrative aryl groups include, but are not limited to, phenyl,naphthalenyl and anthracenyl. The aryl group may be unsubstituted, orsubstituted as described for alkyl or as described in the variousembodiments provided herein. It will be understood that “aryl” may becombined with other groups, to form a functionalized aryl. By way ofexample, the combination of an “C₆-C₁₀ aryl” group, as described herein,with a “C₁-C₆ alkyl” group may be referred to as a —C₁-C₆ alkyl-(C₆-C₁₀aryl).

As used herein, “hydroxy” or ““hydroxyl” refers to an —OH group.

As used herein, “alkoxy” refers to an —O-(alkyl) group, such as an—OC₁-C₆ alkyl. Representative examples include, but are not limited to,methoxy, ethoxy, propoxy, butoxy, cyclopropyloxy, cyclobutyloxy,cyclopentyloxy, cyclohexyloxy, and the like.

As used herein, “aryloxy” refers to an —O-aryl group, such as an—OC₆-C₁₀ aryl.

As used herein, “mercapto” refers to an —SH group.

As used herein, “alkylthio” refers to an —S-(alkyl) or an—S-(unsubstituted cycloalkyl) group. Representative examples include,but are not limited to, methylthio, ethylthio, propylthio, butylthio,cyclopropylthio, cyclobutylthio, cyclopentylthio, cyclohexylthio, andthe like.

As used herein, “arylthio” refers to an —S-aryl or an —S-heteroarylgroup. Representative examples include, but are not limited to,phenylthio, pyridinylthio, furanylthio, thienylthio, pyrimidinylthio,and the like.

As used herein, “cyano” refers to a —CN group.

The term “oxo” represents a carbonyl oxygen. For example, a cyclopentylsubstituted with oxo is cyclopentanone.

As used herein, “halogen” refers to fluorine (F), chlorine (Cl), bromine(Br), and iodine (I). Halogens in their anionic forms or when covalentlybonded to another atom may be alternatively referred to as “halides.”Illustratively, a bond between carbon and a halogen is understood to bea covalent bond and may be alternatively referred to as a carbon-halogenor carbon-halide bond.

As used herein, “bond” refers to a covalent bond.

The term “substituted” means that the specified group or moiety bearsone or more substituents. The term “unsubstituted” means that thespecified group hears no substituents. Where the term “substituted” isused to describe a structural system, the substitution is meant to occurat any valency-allowed position on the system. In some embodiments,“substituted” means that the specified group or moiety bears one, two,or three substituents. In other embodiments, “substituted” means thatthe specified group or moiety bears one or two substituents. In stillother embodiments, “substituted” means the specified group or moietybears one substituent.

As used herein, “optional” or “optionally” means that the subsequentlydescribed event or circumstance may but need not occur, and that thedescription includes instances where the event or circumstance occursand instances in which it does not. For example, “wherein each hydrogenatom in C₁-C₆ alkyl is independently optionally substituted by halogen”means that a halogen may be but need not be present on the C₁-C₆ alkylreplacement of a hydrogen atom for each halogen group, and thedescription includes situations where a C₁-C₆ alkyl, for example, issubstituted with a halogen, and situations where a C₁-C₆ alkyl, forexample, is not substituted with a halogen.

In some embodiments, the process of the present disclosure additionallyincludes a first step comprising contacting a reactant of the formula

wherein X¹ is H, halogen, C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆ alkyl-(C₆-C₁₀aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl, wherein each hydrogen atom inC₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or—OC₆-C₁₀ aryl is independently optionally substituted with a halogen,C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or—OC₆-C₁₀ aryl, with sulfur trioxide. The first step provides a firstproduct mixture that includes a sulfonic acid. In some embodiments, X¹is halogen. In some embodiments, X¹ is Cl.

The first step is generally described by the equation:

Illustratively, the first step may be performed in a first reactionvessel and the product mixture produced by the first step may betransferred to a second reaction vessel after the first step for use ina coupling step.

The product mixture of the first step may comprise a sulfonic acid, anaryl halide, and a sulfone. The sulfonic acid may be chlorobenzenesulfonic acid, the aryl halide may be monocholorbenzene, and thesulfonic may be dichlorodiphenyl sulfone. In some embodiments, the firstproduct mixture comprises about 53% of the sulfonic acid, about 6% ofthe aryl halide, and about 41% of the sulfone.

The process of the present disclosure comprises a coupling stepcomprising contacting a sulfonic acid of the formula

wherein X¹ is a halogen, with an aryl halide of the formula

wherein X² is H, halogen, C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆ alkyl-(C₆-C₁₀aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl, wherein each hydrogen atom inC₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or—OC₆-C₁₀ aryl is independently optionally substituted with a halogen,C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or—OC₆-C₁₀ aryl. In some embodiments, X² is halogen. In some embodiments,X² is Cl.

The coupling step is generally described by the equation:

It is understood that when chemical equations are shown herein,additional reactants, additional reaction components, byproducts,additional products, and impurities that are not shown in the chemicalequations may be present.

It is also understood that during the contacting step of the couplingstep, a bond is formed between a carbon of the aryl halide and thesulfur of sulfur trioxide. Without being bound by theory, the bond mayform as a result of an electrophilic aromatic substitution reaction inwhich sulfur trioxide replaces an aryl hydrogen.

The coupling step occurs in the presence of a catalyst, and resultingwater is removed during the coupling step. As used herein, “resultingwater” describes water formed as a result of the coupling step. Thecombination of a catalyst and the absence of water results in a processthat produces sulfone products in enhanced yields with enhancedselectivity compared to processes known in the art.

In one aspect of the present disclosure, the coupling step may compriseadding the catalyst to the product mixture of the first step. In someembodiments, the catalyst is boric acid.

In another aspect of the present disclosure, the first step and thecoupling steps are separate steps of a batch process. In another aspectof the present disclosure, the first step and the coupling steps areseparate steps of a continuous process. In other embodiments, the firststep is a batch process, and the coupling step is a continuous process.

In some embodiments of the process described herein, X¹ and X² are Cl.In such embodiments, the sulfone is of the formula

When X¹ and X² are Cl, the first step is generally described by theequation:

and the coupling step is generally described by the equation:

As used herein, yield describes the actual amount of a product producedby a reaction relative to the theoretical maximum amount of the productpredicted by a stoichiometric calculation. For example, determiningyield by the sulfone relative to the sulfonic acid may includedetermining the theoretical maximum amount of the sulfone based on thenumber of moles of the sulfonic acid in the initial reaction mixture.Calculating yield is well understood in the art.

As used herein, crude yield describes yield determined after reactionworkup or quenching, prior to additional purification steps. As usedherein, purified yield describes yield determined after reaction workupor quenching and after one or more purification steps.

As previously stated, the process produces sulfone products withenhanced yields. In some embodiments, the crude yield of the couplingstep, as determined by the sulfone relative to the sulfonic acid, isabout 50% to about 100%, about 55% to about 100%, about 60% to about100%, about 65% to about 100%, about 70% to about 100%, about 75% toabout 100%, about 80% to about 100%, about 85% to about 100%, about 50%to about 95%, about 55% to about 95%, about 60% to about 95%, about 65%to about 95%, about 70% to about 95%, about 75% to about 95%, about 80%to about 95%, about 85% to about 95%, about 50% to about 90%, about 55%to about 90%, about 60% to about 90%, about 65% to about 90%, about 70%to about 90%, about 75% to about 90%, about 80% to about 90%, or about85% to about 90%. For example, the crude yield of the coupling step, asdetermined by the sulfone relative to the sulfonic acid, may be about60% to about 95%. Additionally, the crude yield of the coupling step, asdetermined by the sulfone relative to the sulfonic acid, may be about82% to about 93%.

In some embodiments, the purified yield of the coupling step, asdetermined by the sulfone relative to the sulfonic acid, is about 40% toabout 95%, about 45% to about 95%, about 50% to about 95%, about 55% toabout 95%, about 60% to about 95%, about 65% to about 95%, about 70% toabout 95%, about 75% to about 95%, about 80% to about 95%, 40% to about90%, about 45% to about 90%, about 50% to about 90%, about 55% to about90%, about 60% to about 90%, about 65% to about 90%, about 70% to about90%, about 75% to about 90%, about 80% to about 90%, 40% to about 85%,about 45% to about 85%, about 50% to about 85%, about 55% to about 85%,about 60% to about 85%, about 65% to about 85%, about 70% to about 85%,about 75% to about 85%, or about 80% to about 85%. For example, thepurified yield of the coupling step, as determined by the sulfonerelative to the sulfonic acid, may be about 50% to about 85%.Additionally, the purified yield of the coupling step, as determined bythe sulfone relative to the sulfonic acid, may be about 70% to about75%.

It is understood that values preceded by the word “about” include bothan exact value and about that value. For example, “about 90%” describesboth exactly 90% and about 90%.

In some embodiments, the coupling step is initiated under anhydrousconditions. For example, in some embodiments, the coupling step isinitiated with less than about 10 wt % water, less than about 5 wt %water, less than about 1 wt % water, or less than about 0.5 wt % water.In some embodiments, the coupling step is initiated with less than about10 wt % water.

In some embodiments, the resulting water in the coupling step is removedcontinuously during the coupling step. For example, the resulting watermay be removed by distillation.

In certain embodiments, the concentration of water throughout thecoupling step is less than about 10 wt % water, less than about 5 wt %water, less than about 1 wt % water, or less than about 0.5 wt % water.For example, the concentration of water throughout the coupling step maybe less than about 10 wt % water.

In some embodiments, the coupling step is performed without adehydrating reagent. As used herein, a “dehydrating reagent” is areagent that prevents the production of water as a reaction productduring the coupling step by reacting with other reactants involved insulfone formation. An example of a dehydrating reagent istrifluoroacetic anhydride when used with chlorobenzenes and sulfuricacid.

In additional embodiments, the concentration of the catalyst relative toall components of the coupling step, when the coupling step isinitiated, is about 0.1 wt % to about 10 wt %, about 0.1 wt % to about 5wt %, about 0.5 wt % to about 2 wt %, about 0.7 wt % to about 1.1 wt %,or about 0.9 wt %. Illustratively, the concentration of the catalystrelative to all components of the coupling step, when the coupling stepis initiated, may be about 0.1 wt % to about 5 wt %. Additionally, theconcentration of the catalyst relative to all components of the couplingstep, when the coupling step is initiated, may be about 0.7 wt % toabout 1.1 wt %.

Moreover, amount of the catalyst relative to the sulfonic acid, when thecoupling step is initiated, may be about 0.01 equivalent to about 1equivalent, about 0.01 equivalent to about 0.5 equivalent, about 0.01equivalent to about 0.1 equivalent, about 0.01 to about 0.075equivalent, about 0.02 equivalent to about 1 equivalent, about 0.02equivalent to about 0.5 equivalent, about 0.02 equivalent to about 0.1equivalent, about 0.02 to about 0.075 equivalent, about 0.025equivalent, or about 0.05 equivalent. Illustratively, the concentrationof the catalyst relative to the sulfonic acid, when the coupling step isinitiated, may be about 0.01 equivalent to about 0.1 equivalent.Additionally, the concentration of the catalyst relative to the sulfonicacid, when the coupling step is initiated, may be about 0.025 equivalentto about 0.05 equivalent.

In some embodiments, the catalyst is a boron catalyst, an iron catalyst,a zinc catalyst, a tin catalyst, a titanium catalyst, a zirconiumcatalyst, a bismuth catalyst, an antimony catalyst, a silica catalyst, ametal sulfate catalyst, a metal oxide catalyst, a sulfonic acidcatalyst, an iodine catalyst, or a combination thereof. For example, thecatalyst may be aluminum oxide, antimony oxide, zirconium oxide, bismuthoxide, boric anhydride, boric acid, ferric oxide, stannic oxide,titanium oxide, titanium sulfate, zinc oxide, iodine, lithium iodide,methane sulfonic acid, trifluoromethane sulfonic acid, silica, ordimethylsulfate. In certain embodiments, the catalyst may be aluminumoxide. In certain embodiments, the catalyst may be antimony oxide. Incertain embodiments, the catalyst may be zirconium oxide. In certainembodiments, the catalyst may be bismuth oxide. In certain embodiments,the catalyst may be boric anhydride. In certain embodiments, thecatalyst may be boric acid. In certain embodiments, the catalyst may beferric oxide. In certain embodiments, the catalyst may be stannic oxide.In certain embodiments, the catalyst may be titanium oxide. In certainembodiments, the catalyst may be titanium sulfate. In certainembodiments, the catalyst may be zinc oxide. In certain embodiments, thecatalyst may be iodine. In certain embodiments, the catalyst may belithium iodide. In certain embodiments, the catalyst may be methanesulfonic acid. In certain embodiments, the catalyst may betrifluoromethane sulfonic acid. In certain embodiments, the catalyst maybe silica. In certain embodiments, the catalyst may be dimethylsulfate.

In some embodiments, the coupling step results in less than 20% of a2,4′ isomer of the formula

wherein X¹ and X² are independently H, halogen, C₁-C₆ alkyl, C₆-C₁₀)aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl,wherein each hydrogen atom in C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl is independentlyoptionally substituted with a halogen, C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl, as determined bythe 2,4′ isomer relative to all sulfone products. In other embodiments,the coupling step results in less than 10% of the 2,4′ isomer.Illustratively, X¹ and X² may be Cl.

In additional embodiments, the coupling step results in less than 20% ofa 3,4′ isomer of the formula

wherein X¹ and X² are independently H, halogen, C₁-C₆ alkyl, C₆-C₁₀)aryl, —C₁-C₆ alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl,wherein each hydrogen atom in C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₁₀alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl is independentlyoptionally substituted with a halogen, C₁-C₆ alkyl, C₆-C₁₀ aryl, —C₁-C₆alkyl-(C₆-C₁₀ aryl), —OC₁-C₆ alkyl or —OC₆-C₁₀ aryl, as determined bythe 3,4′ isomer relative to all sulfone products. In other embodiments,the coupling step results in less than 10% of the 3,4′ isomer.Illustratively, X¹ and X² may be Cl.

In some embodiments, the coupling step results in less than 20% of a2,4′ isomer of the formula

wherein X¹ and X² are independently halogen, as determined by the 2,4′isomer relative to all sulfone products. In other embodiments, thecoupling step results in less than 10% of the 2,4′ isomer.Illustratively, X¹ and X² may be Cl.

In additional embodiments, the coupling step results in less than 20% ofa 3,4′ isomer of the formula

wherein X¹ and X² are independently halogen, as determined by the 3,4′isomer relative to all sulfone products. In other embodiments, thecoupling step results in less than 10% of the 3,4′ isomer.Illustratively, X¹ and X² may be Cl.

In some embodiments, the aryl halide or aryl compound is added to thesulfonic acid continuously during the coupling step. For example, thearyl halide may be added to the sulfonic acid continuously for about 0.5hour to about 20 hours, about 1 hour to about 20 hours, about 2 hours toabout 20 hours, about 7 hours to about 20 hours, about 9 hours to about20 hours, about 10 hours to about 20 hours, about 0.5 hour to about 15hours, about 1 hour to about 15 hours, about 2 hours to about 15 hours,about 7 hours to about 15 hours, about 9 hours to about 15 hours, about10 hours to about 15 hours, about 0.5 hour to about 13 hours, about 1hour to about 13 hours, about 2 hours to about 13 hours, about 7 hoursto about 13 hours, about 9 hours to about 13 hours, about 10 hours toabout 13 hours, about 0.5 hour to about 12 hours, about 1 hour to about12 hours, about 2 hours to about 12 hours, about 7 hours to about 12hours, about 9 hours to about 12 hours, about 10 hours to about 12hours, or about 10 hours. The aryl halide may be added to the sulfonicacid continuously for about 7 hours to about 13 hours. Additionally, thearyl halide may be added to the sulfonic acid continuously for about 9hours to about 12 hours. Moreover, the aryl halide may be added to thesulfonic acid continuously for about 10 hours.

In some embodiments, the aryl halide or aryl compound is added to thesulfonic acid continuously at the same time that water is removedcontinuously from the sulfonic acid. In certain embodiments, the arylhalide or aryl compound is added to the sulfonic acid continuously atthe same time that wet chlorobenzene is removed continuously from thesulfonic acid.

Illustratively, the aryl halide or aryl compound may be added at a flowrate of about 0.1 mL/min to about 10 mL/min, about 0.5 mL/min to about 5mL/min, about 0.5 mL/min to about 3 mL/min, or about 1.5 mL/min. Morespecifically, the aryl halide may be added at a flow rate of about 1.5mL/min.

In some embodiments, the coupling step is performed at a couplingtemperature of about 150° C. to about 280° C., about 160° C. to about280° C., about 170° C. to about 280° C., about 180° C. to about 280° C.,about 150° C. to about 260° C., about 160° C. to about 260° C., about170° C. to about 260° C., about 180° C. to about 260° C., about 150° C.to about 240° C., about 160° C. to about 240° C., about 170° C. to about240° C., or about 180° C. to about 240° C. In certain embodiments, thecoupling step is performed at a coupling temperature of about 180° C. toabout 240° C.

In one aspect of the present disclosure, the coupling temperature may beincreased during the coupling step. The process may include increasingthe coupling temperature from about 180° C. to about 240° C. during thecoupling step. The coupling temperature may be increased continuouslyfor about 5 minutes to about 120 minutes, about 15 minutes to about 120minutes, about 30 minutes to about 120 minutes, about 45 minutes toabout 120 minutes, about 60 minutes to about 120 minutes, about 90minutes to about 120 minutes, about 5 minutes to about 90 minutes, about15 minutes to about 90 minutes, about 30 minutes to about 90 minutes,about 45 minutes to about 90 minutes, about 60 minutes to about 90minutes, about 5 minutes to about 60 minutes, about 15 minutes to about60 minutes, about 30 minutes to about 60 minutes, about 45 minutes toabout 60 minutes, about 5 minutes to about 45 minutes, about 15 minutesto about 45 minutes, about 30 minutes to about 45 minutes, about 5minutes to about 30 minutes, about 15 minutes to about 30 minutes, orabout 5 minutes to about 15 minutes. In certain embodiments, thecoupling temperature is increased continuously for about 15 minutes toabout 45 minutes. In some embodiments, the coupling temperature isincreased continuously for about 30 minutes.

Another aspect of the present disclosure is that the aryl halide or arylcompound may be added continuously at the same time that the couplingtemperature is increased.

Illustratively, the aryl halide or aryl compound may be the solvent ofthe coupling step.

In some embodiments, the coupling step is performed at a pressure ofabout 15 pounds per square inch (psi) to about 100 psi, about 30 psi toabout 100 psi, about 40 psi to about 100 psi, about 15 psi to about 75psi, about 30 psi to about 75 psi, about 40 psi to about 75 psi, about15 psi to about 60 psi, about 30 psi to about 60 psi, about 40 psi toabout 60 psi, about 15 psi to about 50 psi, about 30 psi to about 50psi, about 40 psi to about 50 psi, or about 45 psi. For example, thecoupling step may be performed at a pressure of about 30 psi to about 60psi. Additionally, coupling step may be performed at a pressure of about45 psi.

In illustrative embodiments, the process includes one or morepurification methods. In some embodiments, the aryl halide or arylcompound is removed from the sulfone after the coupling step. The arylhalide or aryl compound may be removed from the sulfone by distillation.

In certain embodiments, the sulfone is cooled to a quenching temperatureof about 50° C. to about 70° C. For example, the process may includecooling the sulfone to a quenching temperature of about 60° C.

In some embodiments, the process includes extracting the sulfone afterthe coupling step. The sulfone may be extracted with an aromatic solventafter the coupling step. In some embodiments, the sulfone is extractedwith toluene after the coupling step. The extracting step may beperformed after removing the aryl halide or aryl compound from thesulfone. In certain embodiments, the extracting step results in an ambercolored solution comprising the sulfone.

The process of the present disclosure may further comprise washing thesulfone with water. The washing step may be performed after extractingthe sulfone. Illustratively, the washing step may result in the sulfonebeing substantial free of the sulfonic acid.

In certain embodiments, the process may include crystallizing thesulfone. A crystallizing step may be performed after washing andextracting the sulfone. The crystallizing step may result in the sulfonehaving a purity of greater than about 95%. In some embodiments, thecrystallizing step results in the sulfone having a purity of greaterthan about 99%. For example, the crystallizing step may result in thesulfone having a purity of about 99.9%.

In some embodiments, the first step of the process of the presentdisclosure is performed under anhydrous conditions. Specifically, theconcentration of water in the first product mixture may be less thanabout 10 wt % water, less than about 5 wt % water, less than about 1 wt% water, or less than about 0.5 wt % water. In certain embodiments, theconcentration of water in the first product mixture is less than about10 wt % water.

Another aspect of the present disclosure is that the first step mayperformed at a sulfonation temperature of about 30° C. to about 100° C.,about 40° C. to about 100° C., about 50° C. to about 100° C., about 60°C. to about 100° C., about 30° C. to about 90° C., about 40° C. to about90° C., about 50° C. to about 90° C., about 60° C. to about 90° C.,about 30° C. to about 80° C., about 40° C. to about 80° C., about 50° C.to about 80° C., about 60° C. to about 80° C., about 30° C. to about 75°C., about 40° C. to about 75° C., about 50° C. to about 75° C., or about60° C. to about 75° C. In some embodiments, the first step occurswithout external cooling.

Now referring to FIG. 1, a process for preparing dichlorodiphenylsulfone from chlorobenzene sulfonic acid is shown. The process includesa coupling step and a purification step.

The coupling step includes first combining chlorobenzene sulfonic acid,monochlorobenzene (also referred to herein as chlorobenzene), and boricacid in a DCDPS reactor (Step 1). After chlorobenzene sulfonic acid,monochlorobenzene, and boric acid are combined in the DCDPS reactor,monochlorobenzene is added (Step 2) while wet monochlorobenzene isremoved (Step 3). The coupling step results in a crude dichlorodiphenylsulfone mixture.

The purification step includes transferring the crude dichlorodiphenylsulfone mixture to another vessel fitted with a Dean-Stark trap (Step4). Water is added to the crude dichlorodiphenyl sulfone mixture (Step5) while wet monochlorobenzene is removed (Step 6). Dichlorophenylsulfone is obtained by filtration (Step 7). Chlorobenzene sulfonic acidis recovered by evaporation (Step 8).

Advantageously, the process of the present disclosure efficientlyaffords 4,4′-dichlorodiphenylsulfone in high yield and high selectivitywith minimal byproduct formation, as further demonstrated by theExamples below.

EXAMPLES

TABLE 1 Yields and Ratios of Sulfone Isomers for Examples CE-1 and 1-7Isomers Example Yield 4,4′ Isomer 2,4′ Isomer 3,4′ Isomer U.S. patent4,983,773, Example 2 reported results. 84% 84.8% 7.8% 7.4% CE-1 14%60.5% 2.7% 36.8% 1 85% (73%*) 87.3% 8.0% 4.7% 2 89% 86.7% 8.2% 5.1% 382% 88.6% 8.0% 3.4% 4 85% 86.0% 10.0% 4.0% 5 89% 86.4% 8.4% 5.2% 6 87%86.7% 8.2% 5.1% 7 81% 82.1% 10.1% 7.8% *Recrystllized yield

Comparative Example 1 (CE-1): Preparation of 4,4′-DichlorodiphenylSulfone Using Boric Acid Following Procedure of U.S. Pat. No. 4,983,773(Jan. 8, 1991), Example 2

Repetition of the U.S. Pat. No. 4,983,773 process, as described below,resulted in a mixture that could not be purified by the same methodsreported therein. Additionally, repetition of the U.S. Pat. No.4,983,773 process resulted in significantly lower yield andsignificantly lower selectivity than reported therein.

A 0.5 L autoclave fitted with an addition pump for chlorobenzene,backflow regulator, and condenser was charged with 50 g conc. sulfuricacid, 100 g chlorobenzene, and 1.5 g boric acid catalyst. The back flowregulator was set to 65 psi and the contents of the autoclave wereheated to 180° C. at which point condensate began to drip from thecondenser. Chlorobenzene addition was started at a flow rate of 1.5mL/min and heating was continued until the reactor reached 240° C.(approximately 1 hour). The chlorobenzene addition was continued for atotal of 16 hours while distilling off excess chlorobenzene and anywater formed during the reaction. The reactor was cooled to 120° C. theautoclave was opened and found to contain a 69 g of a black tar inunreacted chlorobenzene. Analysis showed it to contain 60.5%4,4′-dichlorodiphenyl sulfone relative to the other dichlorodiphenylsulfone isomers (see Table 1), but many other unidentified byproductswere also present. The amount of 4.4′-dichlorodiphenyl sulfone in thetar corresponded to a 14% yield relative to reacted chlorobenzene.Attempts to separate the desired material from the byproducts wereunsuccessful. This included pouring the tarry reaction crude into waterand extracting the aqueous layer with toluene, chlorobenzene, or2-methyltetrahydrofuran. All extraction attempts resulted in blackemulsions whereby the organic and water components could not beseparated. Attempts also included steam distillation of the reactioncrude to remove volatile materials, but this provided a black emulsionthat could not be filtered.

Example 1: Improved Process for Preparing 4,4′-Dichlorodiphenyl SulfoneUsing Boric Acid Catalyst

A 500 mL round-bottom flask containing 145 g chlorobenzene was treatedwith gaseous 42 g sulfur trioxide over a 3 hour period so as to keep theinternal temperature of the reaction vessel at or below 75° C. withoutexternal cooling. Analysis of the resultant solution showed it tocontain 53.4% 4-chlorobenzenesulfonic acid, 5.8% 4,4′-dichlorodiphenylsulfone, and 40.8% chlorobenzene. This solution (173 g) and 1.5 g boricacid were charged to the autoclave of Example 1. The back flow regulatorwas set to 45 psi and the contents of the autoclave were heated to 180°C. at which point condensate began to drip from the condenser.Chlorobenzene addition was started at a flow rate of 1.5 mL/min andheating was continued until the reactor temperature reached 240° C.(approximately 30 minutes). The chlorobenzene addition was continued fora total of 10 hours while simultaneously removing wet chlorobenzenethough the condenser. At the end of the addition the autoclave contained50 g chlorobenzene, 29.3 g 4-chlorobenzenesulfonic acid, and 102 g of4,4′-dichlorodiphenylsulfone and related isomers (85% yield whenadjusted for unreacted chlorobenzenesulfonic acid and subtraction ofunwanted isomers). The contents of the autoclave were transferred to around-bottom flask fitted with a Dean-Stark trap. The remainingchlorobenzene was then steam distilled from the mixture while returningthe water back into the flask. The resultant grey slurry was cooled to60° C. and extracted twice with toluene. The combined organic layerswere washed once with water, and the combined aqueous extracts dewateredto afford 29.3 g unreacted 4-chlorobenzenesulfonic acid. Analysis of thetoluene extracts determined 87.3% 4,4′-dichlorodiphenylsulfone comparedto the other dichlorodiphenyl sulfone isomers (see Table 1). The ambercolored organic layers were concentrated, and crystallization provided69 g of 99.9% pure 4,4′-dichlorodiphenyl sulfone as colorless needles(73% yield adjusted for unreacted chlorobenzenesulfonic acid).

Example 2: Improved Process for Preparing 4,4′-Dichlorodiphenyl SulfoneUsing Boric Acid Catalyst and Purchased 4-Chlorobenzenesulfonic Acid

The autoclave of example 1 was charged with 104.1 g4-chlorobenzenesulfonic acid (tech grade, 87.4% by weight, 0.47 Mol) and1.5 g boric acid. The back flow regulator was set to 45 psi and thecontents of the autoclave were heated to 180° C. at which pointcondensate began to drip from the condenser. Chlorobenzene addition wasstarted at a flow rate of 1.5 mL/min and heating was continued until thereactor temperature reached 240° C. (approximately 30 minutes). Thechlorobenzene addition was continued for a total of 10 hours whilesimultaneously removing wet chlorobenzene though the condenser. Thecontents of the autoclave were transferred to a round-bottom flaskfitted with a Dean-Stark trap and containing 280 g water. The remaining65 g of chlorobenzene was removed by steam distillation and theresultant grey slurry was cooled and filtered. The filtrate wasdewatered to afford 28.3 g unreacted 4-chlorobenzenesulfonic acid. Thefiltered grey solid was dried to provide 95.4 g of4,4′-dichlorodiphenylsulfone in 86.7% isomeric purity (89% yieldadjusted for unreacted chlorobenzenesulfonic acid).

Example 3: Preparation of 4,4′-Dichlorodiphenyl Sulfone Using FerricOxide Catalyst

The procedure of Example 2 was followed except 0.40 g of ferric oxidewas used in place of boric acid, the chlorobenzene addition rate was 1.0mL/min, and the reaction time was 7.4 hours. 28.3 g of unreacted4-chlorobenzenesulfonic acid was isolated and 82.3 g of4,4′-dichlorodiphenyl sulfone was obtained in 88.6% isomeric purity (88%yield adjusted for unreacted chlorobenzenesulfonic acid).

Example 4: Preparation of 4,4′-Dichlorodiphenyl Sulfone Using StannicOxide Catalyst

The procedure of Example 3 was followed except 3.66 g of stannic oxidewas used in place of boric acid, the chlorobenzene addition rate was 1.0mL/min, and the reaction time was 7.4 hours. 24.4 g unreacted4-chlorobenzenesulfonic acid was isolated and 84.5 g of4,4′-dichlorodiphenyl sulfone was obtained in 88.6% isomeric purity (85%yield adjusted for unreacted chlorobenzenesulfonic acid).

Example 5: Preparation of 4,4′-Dichlorodiphenyl Sulfone Using TitaniumSulfate Catalyst

The procedure of Example 3 was followed except 7.3 g of titanium sulfatewas used in place of boric acid, the chlorobenzene addition rate was 1.0mL/min, and the reaction time was 7.4 hours. 27.4 g unreacted4-chlorobenzenesulfonic acid was isolated and 87.5 g of4,4′-dichlorodiphenyl sulfone was obtained in 86.4% isomeric purity (89%yield adjusted for unreacted chlorobenzenesulfonic acid).

Example 6: Preparation of 4,4′-Dichlorodiphenyl Sulfone Using IodineCatalyst

The procedure of Example 3 was followed except 3.16 g of iodine was usedin place of boric acid, the chlorobenzene addition rate was 1.0 mL/min,and the reaction time was 12 hours. 27.6 g unreacted4-chlorobenzenesulfonic acid was isolated and 91.8 g of4,4′-dichlorodiphenyl sulfone was obtained in 86.7% isomeric purity (87%yield adjusted for unreacted chlorobenzenesulfonic acid).

Example 7: Preparation of 4,4′-Dichlorodiphenyl Sulfone

The procedure of Example 3 was followed except 4.0 g of lithium iodidewas used in place of boric acid, the chlorobenzene addition rate was 1.0mL/min, and the reaction time was 7.4 hours. 44.1 g unreacted4-chlorobenzenesulfonic acid was isolated and 59.7 g of4,4′-dichlorodiphenyl sulfone was obtained in 82.1% isomeric purity (81%yield adjusted for unreacted chlorobenzenesulfonic acid).

Example 8: Improved Process for Preparing 4,4′-Dichlorodiphenyl SulfoneUsing Boric Acid Catalyst (B400-07)

A solution of 100 g monochlorobenzene, 95.20 g chlorobenzene sulfonicacid, and 1.5 g boric acid (0.05 equiv) were charged to the autoclave ofExample 1. The solution contained 7.27 g water. The back flow regulatorwas set to 45 psi and the contents of the autoclave were heated to 180°C. at which point condensate began to drip from the condenser.Chlorobenzene addition was started at a flow rate of 1 mL/min until454.40 g chlorobenzene was added and heating was continued until thereactor temperature reached 240° C. The chlorobenzene addition wascontinued while simultaneously removing wet chlorobenzene though thecondenser. At the end of the addition the autoclave contained 56.00 gchlorobenzene, 35.68 g 4-chlorobenzenesulfonic acid, and 82.30 g of4,4′-dichlorodiphenylsulfone and related isomers (58.0% yield whenadjusted for unreacted chlorobenzenesulfonic acid). The contents of theautoclave were transferred to a round-bottom flask fitted with aDean-Stark trap. The remaining chlorobenzene was then steam distilledfrom the mixture while returning the water back into the flask. Theresultant grey slurry was cooled to 60° C. and extracted twice withtoluene. The combined organic layers were washed once with water, andthe combined aqueous extracts dewatered to afford 35.68 g unreacted4-chlorobenzenesulfonic acid. Analysis of the toluene extractsdetermined 85.8% 4,4′-dichlorodiphenylsulfone, 8.5%2,4′-dichlorodiphenylsulfone, and 5.7% 3,4′-dichlorodiphenylsulfone,each compared to the other dichlorodiphenyl sulfone isomers.

Example 9: Improved Process for Preparing 4,4′-Dichlorodiphenyl SulfoneUsing Ferric Oxide Catalyst (B400-08)

A solution of 100 g monochlorobenzene, 95.75 g chlorobenzene sulfonicacid, and 0.40 g Fe₂O₃ (0.025 equiv) were charged to the autoclave ofExample 1. The solution contained 7.32 g water. The back flow regulatorwas set to 45 psi and the contents of the autoclave were heated to 180°C. at which point condensate began to drip from the condenser.Chlorobenzene addition was started at a flow rate of 1 mL/min until452.20 g chlorobenzene was added and heating was continued until thereactor temperature reached 240° C. The chlorobenzene addition wascontinued while simultaneously removing wet chlorobenzene though thecondenser. At the end of the addition the autoclave contained 39.00 gchlorobenzene, 36.17 g 4-chlorobenzenesulfonic acid, and 82.29 g of4,4′-dichlorodiphenylsulfone and related isomers (57.6% yield whenadjusted for unreacted chlorobenzenesulfonic acid). The contents of theautoclave were transferred to a round-bottom flask fitted with aDean-Stark trap. The remaining chlorobenzene was then steam distilledfrom the mixture while returning the water back into the flask. Theresultant grey slurry was cooled to 60° C. and extracted twice withtoluene. The combined organic layers were washed once with water, andthe combined aqueous extracts dewatered to afford 36.17 g unreacted4-chlorobenzenesulfonic acid. Analysis of the toluene extractsdetermined 88.6% 4,4′-dichlorodiphenylsulfone, 8.0%2,4′-dichlorodiphenylsulfone, and 3.4% 3,4′-dichlorodiphenylsulfone,each compared to the other dichlorodiphenyl sulfone isomers.

Example 10: Improved Process for Preparing 4,4′-Dichlorodiphenyl SulfoneUsing Stannic Oxide Catalyst (B400-24)

A solution of 100 g monochlorobenzene, 95.80 g chlorobenzene sulfonicacid, and 3.66 g SnO₂ (0.05 equiv) were charged to the autoclave ofExample 1. The solution contained 7.32 g water. The back flow regulatorwas set to 45 psi and the contents of the autoclave were heated to 180°C. at which point condensate began to drip from the condenser.Chlorobenzene addition was started at a flow rate of 1 mL/min until482.20 g chlorobenzene was added and heating was continued until thereactor temperature reached 240° C. The chlorobenzene addition wascontinued while simultaneously removing wet chlorobenzene though thecondenser. At the end of the addition the autoclave contained 47.00 gchlorobenzene, 34.45 g 4-chlorobenzenesulfonic acid, and 84.50 g of4,4′-dichlorodiphenylsulfone and related isomers (59.2% yield whenadjusted for unreacted chlorobenzenesulfonic acid). The contents of theautoclave were transferred to a round-bottom flask fitted with aDean-Stark trap. The remaining chlorobenzene was then steam distilledfrom the mixture while returning the water back into the flask. Theresultant grey slurry was cooled to 60° C. and extracted twice withtoluene. The combined organic layers were washed once with water, andthe combined aqueous extracts dewatered to afford 34.45 g unreacted4-chlorobenzenesulfonic acid. Analysis of the toluene extractsdetermined 86.0% 4,4′-dichlorodiphenylsulfone, 10.0%2,4′-dichlorodiphenylsulfone, and 4.0% 3,4′-dichlorodiphenylsulfone,each compared to the other dichlorodiphenyl sulfone isomers.

Example 11: Improved Process for Preparing 4,4′-Dichlorodiphenyl SulfoneUsing Titanium Sulfate Catalyst (B400-29)

A solution of 100 g monochlorobenzene, 95.80 g chlorobenzene sulfonicacid, and 1.5 g TiSO₄ were charged to the autoclave of Example 1. Thesolution contained 7.32 g water. The hack flow regulator was set to 45psi and the contents of the autoclave were heated to 180° C. at whichpoint condensate began to drip from the condenser. Chlorobenzeneaddition was started at a flow rate of 1 mL/min until 473.70 gchlorobenzene was added and heating was continued until the reactortemperature reached 240° C. The chlorobenzene addition was continuedwhile simultaneously removing wet chlorobenzene though the condenser. Atthe end of the addition the autoclave contained 49.00 g chlorobenzene,37.36 g 4-chlorobenzenesulfonic acid, and 87.50 g of4,4′-dichlorodiphenylsulfone and related isomers (61.3% yield whenadjusted for unreacted chlorobenzenesulfonic acid). The contents of theautoclave were transferred to a round-bottom flask fitted with aDean-Stark trap. The remaining chlorobenzene was then steam distilledfrom the mixture while returning the water back into the flask. Theresultant grey slurry was cooled to 60° C. and extracted twice withtoluene. The combined organic layers were washed once with water, andthe combined aqueous extracts dewatered to afford 37.36 g unreacted4-chlorobenzenesulfonic acid. Analysis of the toluene extractsdetermined 86.4% 4,4′-dichlorodiphenylsulfone, 8.4%2,4′-dichlorodiphenylsulfone, and 5.2% 3,4′-dichlorodiphenylsulfone,each compared to the other dichlorodiphenyl sulfone isomers.

Example 12: Improved Process for Preparing 4,4′-Dichlorodiphenyl SulfoneUsing Iodine Catalyst (B400-36)

A solution of 74.77 g monochlorobenzene, 89.41 g chlorobenzene sulfonicacid, and 1.5 g I₂ were charged to the autoclave of Example 1. Thesolution contained 0.1 g water and 7.74 g dichlorodiphenylsulfone. Theback flow regulator was set to 45 psi and the contents of the autoclavewere heated to 180° C. at which point condensate began to drip from thecondenser. Chlorobenzene addition was started at a flow rate of 1 mL/minuntil 760.84 g chlorobenzene was added and heating was continued untilthe reactor temperature reached 240° C. The chlorobenzene addition wascontinued while simultaneously removing wet chlorobenzene though thecondenser. At the end of the addition the autoclave contained 48.00 gchlorobenzene, 28.90 g 4-chlorobenzenesulfonic acid, and 91.80 g of4,4′-dichlorodiphenylsulfone and related isomers (68.9% yield whenadjusted for unreacted chlorobenzenesulfonic acid). The contents of theautoclave were transferred to a round-bottom flask fitted with aDean-Stark trap. The remaining chlorobenzene was then steam distilledfrom the mixture while returning the water back into the flask. Theresultant grey slurry was cooled to 60° C. and extracted twice withtoluene. The combined organic layers were washed once with water, andthe combined aqueous extracts dewatered to afford 28.90 g unreacted4-acid. Analysis of the toluene extracts determined 86.7%4,4′-dichlorodiphenylsulfone, 8.2% 2,4′-dichlorodiphenylsulfone, and5.1% 3,4′-dichlorodiphenylsulfone, each compared to the otherdichlorodiphenyl sulfone isomers.

Example 13: Improved Process for Preparing 4,4′-Dichlorodiphenyl SulfoneUsing Lithium Iodide Catalyst (B400-40)

A solution of 105.00 g monochlorobenzene, 96.70 g chlorobenzene sulfonicacid, and 1.5 g LiI were charged to the autoclave of Example 1. Thesolution contained 7.39 g water. The back flow regulator was set to 45psi and the contents of the autoclave were heated to 180° C. at whichpoint condensate began to drip from the condenser. Chlorobenzeneaddition was started at a flow rate of 1 mL/min until 487.70 gchlorobenzene was added and heating was continued until the reactortemperature reached 240° C. The chlorobenzene addition was continuedwhile simultaneously removing wet chlorobenzene though the condenser. Atthe end of the addition the autoclave contained 35.00 g chlorobenzene,44.10 g 4-chlorobenzenesulfonic acid, and 59.73 g of4,4′-dichlorodiphenylsulfone and related isomers (41.4% yield whenadjusted for unreacted chlorobenzenesulfonic acid). The contents of theautoclave were transferred to a round-bottom flask fitted with aDean-Stark trap. The remaining chlorobenzene was then steam distilledfrom the mixture while returning the water back into the flask. Theresultant grey slurry was cooled to 60° C. and extracted twice withtoluene. The combined organic layers were washed once with water, andthe combined aqueous extracts dewatered to afford 44.10 g unreacted4-chlorobenzenesulfonic acid. Analysis of the toluene extractsdetermined 82.1% 4,4′-dichlorodiphenylsulfone, 10.1%2,4′-dichlorodiphenylsulfone, and 7.8% 3,4′-dichlorodiphenylsulfone,each compared to the other dichlorodiphenyl sulfone isomers.

Example 14: Survey of Catalysts

A series of catalysts were surveyed for the production of DCDPS usingthe following general procedure.

A reaction vessel was charged with 113 g of chlorobenzene and catalyst(See table 2 for catalysts and amounts used). A gentle flow of SO₃ wasintroduced into the reaction vessel until a total of 41.5 g of SO₃ wasdelivered to the reaction vessel. During this time, the internaltemperature of the reaction vessel reached a maximum of 75° C. Themixture was heated to 200° C. during and most of the solvent distilledoff. This hot residue was treated with 275 g chlorobenzene over a 4 hourperiod via syringe pump while driving off excess chlorobenzene and anywater formed. At the end of the 4 hour period, the reaction was quenchedwith water (125 mL) and the resultant solid filtered and air dried for3-4 hours to provide crude DCDPS as a grey solid.

TABLE 2 Yields of Sulfone from Example 14 Catalyst DCDPS (equiv.) YieldCH₃SO₄CH₃ 26% (0.05 equiv) PO(OCH₃)₃ 12% (0.05 equiv) CH₃SO₃H 29% (0.01equiv) CF₃SO₃H 32% (0.01 equiv) ZnO 31% (0.01 equiv) ZrO₂ 34% (0.01equiv) Bi₂O₃ 31% (0.01 equiv) Sb₂O₃ 29% (0.01 equiv) B₂O₃ 34% (0.01equiv)

1.-82. (canceled)
 83. A process for preparing a sulfone of the formula

wherein X¹ and X² are independently H, halogen, or C₁-C₆ alkyl, whereineach hydrogen atom in C₁-C₆ alkyl is independently optionallysubstituted with a halogen or C₁-C₆ alkyl; the process comprising a.contacting a reactant of the formula

wherein X¹ is a H, halogen, C₁-C₆ alkyl, wherein each hydrogen atom inC₁-C₆ alkyl is independently optionally substituted with a halogen orC₁-C₆ alkyl, with sulfur trioxide to provide a first product mixturecomprising the sulfonic acid to provide a sulfonic acid of the formula

and b. a coupling step comprising contacting the sulfonic acid formed instep (a) with an aryl compound of the formula

wherein X² is a H, halogen, or C₁-C₆ alkyl, wherein each hydrogen atomin C₁-C₆ alkyl is independently optionally substituted with a halogen orC₁-C₆ alkyl, in the presence of a catalyst selected from the groupconsisting of aluminum oxide, antimony oxide, zirconium oxide, bismuthoxide, boric anhydride, boric acid, ferric oxide, stannic oxide,titanium oxide, titanium sulfate, zinc oxide, iodine, lithium iodide,and silica, wherein resulting water is removed during the coupling step(b) by distillation, and wherein the coupling step (b) is performed inthe absence of a dehydrating reagent.
 84. The process of claim 83,wherein step (a) is performed at a temperature in the range of about 30°C. to about 100° C.
 85. The process of claim 84, wherein the couplingstep (b) is performed at a temperature in the range of about 180° C. toabout 240° C.
 86. The process of claim 85, wherein X′ and X′ are Cl. 87.The process of claim 85, wherein the crude yield of the coupling step(b), as determined by the sulfone relative to the sulfonic acid, isabout 60% to about 95%.
 88. The process of claim 85, wherein thepurified yield of the coupling step (b), as determined by the sulfonerelative to the sulfonic acid, is about 50% to about 85%.
 89. Theprocess of claim 85, wherein the coupling step (b) is initiated underanhydrous conditions.
 90. The process of claim 85, wherein the couplingstep (b) is initiated with less than about 10 wt % water.
 91. Theprocess of claim 85, wherein the resulting water is removed continuouslyduring the coupling step (b).
 92. The process of claim 85, wherein step(a) is performed in a first reaction vessel and the product mixtureproduced by step (a) is transferred to a second reaction vessel afterthe first step for use in step (b).
 93. The process of claim 85, whereinthe concentration of water throughout the coupling step (b) is less thanabout 10 wt % water.
 94. The process of claim 85, wherein theconcentration of the catalyst relative to all components of the couplingstep, when the coupling step (b) is initiated, is about 0.7 wt % toabout 1.1 wt %.
 95. The process of claim 85, wherein the coupling stepresults in less than 20% of a 2,4′ isomer of the formula

wherein X¹ and X² are independently H, halogen, or C₁-C₆ alkyl, whereineach hydrogen atom in C₁-C₆ alkyl is independently optionallysubstituted with a halogen or C₁-C₆ alkyl, as determined by the 2,4′isomer relative to all sulfone products.
 96. The process of claim 85,wherein the coupling step results in less than 20% of a 3,4′ isomer ofthe formula

wherein X¹ and X² are independently H, halogen, or C₁-C₆ alkyl, whereineach hydrogen atom in C₁-C₆ alkyl is independently optionallysubstituted with a halogen or C₁-C₆ alkyl, as determined by the 3,4′isomer relative to all sulfone products.
 97. The process of claim 85,wherein the aryl compound in coupling step (b) is added to the sulfonicacid continuously at the same time that water is removed continuouslyfrom the sulfonic acid.
 98. The process of claim 85, wherein the arylcompound in coupling step (b) is added to the sulfonic acid continuouslyat the same time that wet chlorobenzene is removed continuously from thesulfonic acid.
 99. The process of claim 85, wherein the aryl compound incoupling step (b) is added at a flow rate of about 1.5 mL/min.
 100. Theprocess of claim 85, wherein the coupling step (b) is performed at apressure of about 30 psi to about 60 psi.
 101. The process of claim 85,further comprising extracting the sulfone after the coupling step (b).102. The process of claim 85, further comprising crystallizing thesulfone.